In the commercial production of farinaceous compositions the finished product must have a low moisture content and a low water activity to render the product shelf stable. Food products are generally considered shelf stable when the water activity is below about 0.7. Dough products that are intended to be formed into dough pieces and baked by the consumer typically have a high moisture content and must be refrigerated to maximize shelf-life. A typical cookie dough formulation will have a moisture content of 13% and a water activity greater than 0.75. The high moisture content is generally considered necessary to control the oven spread and rise of the dough and to make the dough easy to handle.
Efforts to improve the shelf stability and lower the water activity may typically include a drying step to reduce the amount of water in the product. Alternatively, water activity reducing components may be included, such as sorbitol, fructose or other sugars.
It is known that microwave cooking in general decreases the time that is required in order to cook a substance. One reason for this is that the microwave radiation penetrates throughout the item being cooked thereby internally heating and cooking the item. There have been particular problems with regard to using microwave ovens as a means for baking various products. For instance, in the baking of bread using microwave ovens there was always the need to use a conventional oven in a final step to brown the loaf of bread. Further, the use of microwave energy did not produce a consistent texture throughout the interior portion of the loaf. In general, the bread loaves tend to collapse and to have a poor, rubbery interior structure. In the baking of cakes it was found that when a cake batter is baked in a microwave oven, the outer edges become dry and tough before the center is completely baked. Further, the texture of the cake is not the same as if the cake had been baked in a convection oven. That is, a moist, light, uniform air cell texture is not produced. Further, there is the added problem that the cake would not be browned in the microwave oven. If the cake is not to contain an icing to cover the surface, a final step of baking in a conventional oven would be required in order to produce the consumer-desired brown appearance to the cake's surface.
In the production of a high oil content farinaceous composition by extrusion, cooking, mobility and immiscibility of the water and oil phases generally increase with increasing temperature. Additionally, the mechanical action of extruder screws tends to increase separation of oil from the remaining mass. The tendency for the oil to separate is at locations within the extruder at which the components are subjected to the highest pressure. Exemplary of high pressure locations in a twin screw extruder are: 1) the space between the extruder screw tips and the die orifice, and 2) the narrowest or more restricted passageways between the left and right hand screw elements.
Oil separation under system pressure (screw or die pressure) can be manifested in extruder surging or uneven mass flow rates from the die. Upon extrusion from the die, separated oil may: 1) appear as a coating on the remaining dough mass, or 2) periodically discharge separately from the remaining dough mass. Non-homogeneous dough production and discontinuous extruder operation may thus result from oil separation. The problem of oil separation increases with increasing oil levels.
Water separation from flour, up to the boiling point of water, is generally not a problem because of the more hydrophilic properties of flour components such as gluten and starch. As flour and water temperatures are raised, increased migration of water into starch granules, protein (e.g. gluten) denaturization, and starch gelatinization tend to occur. The binding or reaction of water with flour components may promote separation of oil: a) by making the flour components more polar or hydrophilic and b) by creating a greater mass of hydrophilic components.
Conventional cookie production involves forming cookie dough preforms or pieces followed by baking of the pieces. Low temperatures, typically at about room temperature, are used to form the dough. The low temperature mixing generally avoids separation of shortening or fat from hydrophilic dough components. While baking temperatures in a conventional oven, such as a band oven, may promote oil separation, there is no mixing or pressing action performed at the baking temperatures. Any oil separation which may occur in such ovens does not generally interfere with continuous operability of the cookie production process as it would in a continuous cooker/extruder process.
In addition to high temperature mixing and high system pressure, the presence of sugar in a cookie dough may also increase oil and water separation. Solubilization of sugars in water increases the relative amount of the hydrophilic mass. This in turn may tend to promote oil separation.
The elimination or significant reduction of added water or a source of added water in a cooker extruder tends to reduce oil separation from hydrophilic cookie dough components at elevated temperatures. However, added water or a source of water is needed in cookie production for formability or machinability of cookie doughs into sheets or pieces at high production rates. Water also helps to disperse cookie ingredients and to promote flavor and color development.
Cookies containing edible particles, such as chocolate chips, are usually formed by preparing the dough in a suitable blender, such as a ribbon blender. After the dough is formed, the particles are added to the prepared dough and gently mixed to uniformly distribute the particles throughout the dough. The dough and the particles are then transferred to a suitable dough shaping and cutting apparatus. This procedure often results in the destruction of the shape of the particle as well as its taste, texture, color and identity. Many of the edible particles are relatively soft and cannot withstand extreme mixing or high shear for extended periods of time. For example, chocolate chips might lose their shape during mixing, particularly if the dough is warmed. Nut pieces are also sensitive to high shear and cannot be subjected to extensive mixing. High shear will reduce the nuts to a meal or paste and result in oil separation in the mixing apparatus.
Processes have been proposed to apply the edible particles to the surface of the product during different stages of the dough piece formation. Securing the particles to the surface of the dough has shown to be difficult either before or after baking. During the baking, cooling and packaging stages of the cookie production, large quantities of the edible pieces become dislodged resulting in a product that is unsatisfactory to the consumer. In addition, the edible particle processing stage and loss of the edible particles from the product increase the final manufacturing costs.
The present invention is directed to a method of preparing a shelf stable cookie composition which may have optional heat and shear sensitive components uniformly distributed through the composition. Specifically, the invention relates to an extrusion process for producing a cookie dough-like composition where the ingredients are heat treated in a heating zone and cooled before the heat and shear sensitive particles are admixed into the composition. The edible particles are added under low shear conditions to prevent breaking the particles. The cookie composition containing the edible particles has a low water content and a low water activity resulting in a product having improved shelf stability. The shelf-stable cookie composition can be leavened to a crumb-like structure.